With high temperatures expected over the coming days, the Ottawa Humane Society is reminding people not to leave their pets in cars on hot days for any length of time, even with windows rolled down.

Bruce Roney, executive director of the Ottawa Humane Society, said he's amazed people still leave their pets unattended in vehicles on sunny days. (CBC)

In June and July, three dog owners were charged by the society after their pets were left unattended in locked cars on hot days. In all three cases, the dogs were suffering from heat stress, the society said.

Miriam Smith, a rescue inspector, said the society has responded to 117 heat-related calls already this season.

"The amazing thing is it's still happening," said the society's executive director, Bruce Roney. "People still seem to think that it's OK to take their dog out, leave them in a hot car. Cracking a window is not enough. The temperature goes sky high very, very quickly, even on a mild day.

"And I'm just stunned that in this day and age, people are still doing this."

Amica Hewitt was working at a restaurant in the ByWard Market several years ago when someone ran into the restaurant, complaining that two older pugs had been left in a car.

It happened during a heat wave. The sunroof and windows were slightly open, Hewitt said.

Amica Hewitt said she helped rescue two pugs from a hot car in the ByWard Market several years ago. (CBC)

She poured water through the sunroof and dialed 911. She was told to call the humane society.

Instead, she flagged down a police officer. He helped her open the car to get the dogs out.

"I brought them into the restaurant. They couldn't hold themselves up. It was really a sad situation," Hewitt said.

The owners were given a ticket and left, Hewitt said. The humane society took the animals in to treat them and told Hewitt they'd decide if the animals would go back to their owners.

The humane society said it's best on hot days to leave pets in a cool place with lots of water.